Napolitani, E.; Kuznetsov, A.; Skorupa, W.; Foad, M.
This volume contains the proceedings of Symposium U Si-based Materials for Advanced Microelectronic Devices: Synthesis, Defects and Diffusion that was held in Nice (France) from the 29th of May to the 2nd of June 2006 during the E-MRS IUMRS ICEM 2006 Spring Meeting. The Symposium was organized by Enrico Napolitani (MATIS  CNR-INFM, Padova, Italy), Andrej Kuznetsov (University of Oslo, Norway), Wolfgang Skorupa (Forschungszentrum Rossendorf, Dresden, Germany), and Majeed Foad (Applied Materials, Sunnyvale CA, USA).As classical scaling of CMOS devices is slowing down, being progressively replaced by performance engineering, new approaches are becoming object of more and more intense research, such as strain engineering, new materials, and advanced annealing methods. Topics of the Symposium were new materials such as strained Si, Si1−xGex, concerning issues on defects, diffusion, ion implantation and on their synthesis. But also, and mainly, research on ultra shallow junctions for future Si CMOS devices, spanning from the investigation of new methods for their formation to the fundamental understanding of dopants and defects. 113 contributions were selected from about 30 countries around the world (including Europe, Americas, Africa and Asia). The presentations were organized in 10 oral technical sessions and two poster sessions, including 14 invited speakers, 37 oral presentations and 62 posters.The organizers of Symposium U would like to thank all participants for their valuable contribution and their active participation, which made the Symposium a very stimulating and lively forum for academic and industrial researchers. Special thanks are due to all the invited speakers for the excellent reviews of their recent work and the state-of-the-art of the actual research activities, and for their brilliant chairing of the sessions. We acknowledge also the significant sponsorship of Applied Materials, which make us capable to provide financial support to some participants and grants to the award winners.
Keywords:
Ion implantation, Millisecond annealing, Synthesis, Defects, Diffusion, Doping, Si CMOS devices, Ultra shallow junctions, Boron clustering, Process simulation, Characterization

Haase, C.; Bergmann, R.; Oswald, J.; Pietzsch, J.
There is increasing interest in targeting peptide receptors and their ligands for tumor diagnostics and therapy since there is evidence that various of these receptors are overexpressed in tumors compared to their expression in normal tissues. Among these receptors playing a key role in tumor progression is the neurotensin receptor (NTR) family. The present study investigated the expression of NTR in HT29 cells (human colon adenocarcinoma), in FaDu cells (human squamous cell carcinoma), and in the corresponding HT-29 and FaDu xenografts in nude mice as a well characterized animal tumor model. Quantitative RT-PCR with specific primers for the three NTR subtypes was done to study mRNA expression. Receptor protein expression was analysed by in vitro autoradiography using [3H]neurotensin(8-13) and by immunohistochemistry with specific antibodies against the three neurotensin receptors NTR1, NTR2, and NTR3. Analysis of receptor mRNA revealed a strong expression of NTR3 and a weaker expression of NTR1 and NTR2. Looking at protein levels, strong signals for NTR1 and NTR2 (NTR1 > NTR2) were detected immunohistochemically both in tumor cells and the corresponding xenografts. In contrast, expression of NTR3 revealed only a very weak immunopositive staining in tumors. Because it is the receptor protein that is targeted in vivo, the enhanced expression of NTR1 and NTR2 in these tumor entities could be a useful target for diagnostics, e.g., with radioligands suitable for single photon or positron emission tomography.

CFX simulations of ROCOM slug mixing experiments

Moretti, F.; Melideo, D.; DAuria, F.; Höhne, T.; Kliem, S.
The present paper documents the CFD code validation activity carried out at the University of Pisa. In particular, the ANSYS CFX-10.0 code has been used to simulate one of the experiments conducted at the ROCOM mixing test facility (FZD, Germany), that reproduced the injection of a de-borated slug in one cold leg of a pressurized water reactor (simulated by a salt tracer) with all circulation pumps at steady-state operation. The calculations were run on several grids obtained through different meshing strategies and having different sizes. The numerical results, in terms ofnormalized concentration of the transported passive scalar in the downcomer and at the core inlet, were compared against corresponding values obtained through experimental measurements of electrical conductivity in the ROCOM facility. Such comparison resulted in a general good qualitative agreement between simulations and experiments, while some discrepancies were evidenced from a quantitative point of view, mainly due to grid coarseness and low order numerical schemes.
Keywords:
ROCOM, CFD

Anisotropy of ion-induced amorphous-crystalline ripples in silicon

Grigorian, S.; Grenzer, J.; Biermanns, A.; Hazra, S.; Datta, D. P.; Chini, T. K.; Sanyal, M. K.; Pietsch, U.
The morphological evolution of surfaces during ion-beam irradiation has attracted significant interest due to possibility of the evelopment and the controlling of self-organization in nanostructures. Pattering and texture on nanometer length scale at metal and semiconductor surfaces has become a topic of intense research. In particular the surface and subsurface ripple formation under 40Ar+ ion-beam irradiation of Si (100) crystal has been studied recently. Based on transmission electron microscopy (TEM), atomic force microscopy (AFM) and x-ray analysis a dramatic effect of the ripple formation was found at an irradiation energy of 60 keV.Apart from the crystalline part, the amorphization process is very important for understanding the amorphous-crystalline interface and the ripple formation mechanism. The dose of the ion beam was varied in the range from low 3e16 up to high 7e17 ions/cm^2 at an incident angle of 60° and an energy of 60 keV. Keeping the optimized irradiation parameters constant we have measured the degree of amorphization as a function of Ar+ dose by means of x-ray grazing incidence amorphous scattering (GIAS). For irradiated samples we found two broad peaks indicating a short-range ordering of amorphous material which does what with the penetration depth of probing x-ray. GIAS profiles probed at different azimuthal angles display a strong anisotropy of the amorphous scattering. The strong damage of the crystalline structure takes place along particular crystallographic directions. This is for the directional anisotropy: and strongly reveal for low doses, before it becomes completly amorphous and mostly uniform at high doses of implantation. Such behavior can be explained taking into account the anisotropy of the crystalline material and orientation of the ion beam with respect crystallographic orientation of the substrate material. This work was supported by the DST-DAAD India-Germany Collaborative Program. We are grateful to ID1 beamline staff for the support at ESRF.

Linkage between the intramembrane H-bond network around aspartic acid 83 and the cytosolic environment of helix 8 in photoactivated rhodopsin

Lehmann, N.; Alexiev, U.; Fahmy, K.
Understanding the coupling between conformational changes in the intramembrane domain and at the membrane-exposed surface of the bovine photoreceptor rhodopsin, a prototypical G protein-coupled receptor (GPCR), is crucial for the elucidation of molecular mechanisms in GPCR activation. Here, we have combined FTIR- and fluorescence spectroscopy to address the coupling between conformational changes in the intramembrane region around the retinal and the environment of helix 8, a putative cytosolic surface switch region in class-I GPCRs. Using FTIR / fluorescence cross-correlation we show specifically that surface alterations monitored by emission changes of fluorescein bound to Cys316 in helix 8 of rhodopsin are highly correlated with (i) H-bonding to Asp83 proximal of the retinal Schiff base but not to Glu122 close to the -ionone and (ii) with a MII-specific 1643 cm-1 IR absorption change, indicative of a partial loss of secondary structure in helix 8 upon MII formation. These correlations are disrupted by limited C-terminal proteolysis but are maintained upon binding of a transducin -subunit (Gt -derived peptide, which stabilizes the MII state. Our results suggest that additional C-terminal cytosolic loop contacts monitored by an amide II absorption at 1557 cm-1 play a functionally crucial role in keeping helix 8 in the position in which its environment is strongly coupled to the retinal-binding site near the Schiff base. In the intramembrane region, this coupling is mediated by the H-bonding network that connects Asp83 to the NPxxY(x)F motif preceding helix 8.
Keywords:
long-range coupling in rhodopsin, FTIR spectroscopy, site-directed fluorescence labeling, heterospectral cross correlation, conformational switch, GPCR signaling

[1-11C]Acetate uptake is not increased in renal cell carcinoma

Kotzerke, J.; Linné, C.; Meinhardt, M.; Steinbach, J.; Wirth, M.; Baretton, G.; Abolmaali, N.; Beuthien-Baumann, B.
Purpose The purpose of this study was to investigate the potential of [1-11C]acetate (AC) as a metabolic tracer for renal cell cancer in human subjects.Methods Twenty-one patients with suspected kidney tumours were investigated with AC and dynamic PET. AC uptake was scored on a five-step scale. Tumour localisation was known from CT/MRI. Histology was available in 18/21 patients. The results in these 18 patients are reported.Results AC uptake by the tumour was less than (n=11), equal to (n=5) or higher than (n=2) uptake in the surrounding renal parenchyma. Histological tumour types showed a typical distribution, with a predominance of clear cell carcinomas (n=14) and only a small number of papillary cell carcinomas (n=2) and oncocytomas (n=2). Only the benign oncocytomas were highly positive with AC.Conclusion In most kidney tumours the AC accumulation was not higher than in normal kidney parenchyma. Therefore, AC PET cannot be recommend for the characterisation of a renal mass.
Keywords:
[1-11C]acetate, Kidney tumour, Positron emission tomography

Detection of neutrons with kinetic energy from 24 keV to 1.2 MeV with long plastic scintillators

Beyer, R.; Grosse, E.; Heidel, K.; Junghans, A. R.; Klug, J.; Légrády, D.; Wagner, A.; Nolte, R.; Röttger, S.
Proton recoil detectors for neutron time-of-flight measurements have been developed, which have a good time and position resolution and at the same time a relatively high efficiency for neutrons with kinetic energies of about 30 keV.
Keywords:
neutron detector, time of flight, ELBE

A new method of improving the acceleration voltage stability of Van de Graaff accelerators

Bürger, W.; Lange, H.; Petr, V.
The relative energy stability of Van de Graaff type ion accelerators is typically limited to some 10-4. An inexpensive possibility to improve this situation was developed at the Forschungszentrum Dresden-Rossendorf. The method refers to the relatively stable periodic pattern of the acceleration voltage fluctuation in such accelerators. Future values of that fluctuation can be predicted with a high degree of certainty and can taken into account in the belt generator control in spite of the belt convolution caused fundamental reaction delay. The microcontroller based implementation of a predictive fluctuation compensation improves the relative acceleration voltage short time stability by a factor of 36 to well below 10-4.
Keywords:
Van de Graaff; Ion accelerators; Energy stability; Voltage fluctuation compensation; Predictive control

Nuclear Instruments and Methods in Physics Research A 586(2008), 160-168

Study of the textural evolution in Ti-rich NiTi using synchrotron radiation

Paula, A. S.; Canejo, J. H. P. G.; Mahesh, K. K.; Silva, R. J. C.; Braz Fernandez, F. M.; Martins, R. M. S.; Cardoso, A. M. A.; Schell, N.
The aim of the present work is to investigate the textural evolution in high-temperature phase (austenite  B2) of Ti-rich NiTi (Ni51at%Ti) shape memory alloys (SMA). The alloy was subjected to different thermomechanical treatments involving various heat treatments and cold rollings (10% and 40%). The qualitative texture analysis was performed at BM20 (ROBL-CRG) of the European Synchrotron Research Facility (ESRF) using in-situ high-temperature X-ray diffraction (XRD) with a wavelength of 0.154 nm. In-situ high-temperature texture determination has been carried out for the first time for NiTi alloys, by annealing at different temperatures up to 800 °C under a vacuum better than 1e-4 Pa. The discussion highlights the evolution of texture during annealing at high temperatures and the change in the coherency domain size and microstrain.
Keywords:
Ti-rich NiTi; Shape memory alloy; In-situ high-temperature XRD; Texture; Synchrotron radiation

What to expect from next generation liquid metal experiments on dynamo action and magnetorotational instability?

Stefani, F.; Gerbeth, G.
After a short summary of the achievements made in liquid metal experiment during the last seven years, we try to identify some important points which should be addressed by next generation experiments. These include the role of rotation and precession, the role of large scale and small scale fluctuations on the dynamo threshold, the occurrence of field reversals in highly supercritical states and further studies of the magnetorotational instability in cylindrical, spherical and oblate geometries.

Electronegativity and point defect formation in ion implanted SiO2 layers

Prucnal, S.; Sun, J.; Reuther, H.; Skorupa, W.; Buchal, C.
The Metal-Oxide-Silicon (MOS) diode structure containing ion implanted electropositive (M+) and electronegative (M-) ions is one of the most promising candidates for a new type of high-efficiency electroluminescence (EL) devices which can be integrated with standard silicon CMOS technology. The implantation process creates defects in the SiO2 layer. After implantation an annealing process leads to the diffusion of the implanted elements and a broadening of the SiO2/Si interface. The influence of the different implanted ions (Gd, F, K) was investigated by electroluminescence measurements and correlated to different defects in the oxide layer. Implanted electronegative ions (such as F) lead defects comprising O2 molecules and peroxy radicals (POR). On the other hand, the electropositive ions (Gd and K) increase the number of the oxygen vacancy defects.
Keywords:
ion implantation, electronegativity, electroluminescence

Lecture (Conference)
VI-th International Conference on Ion Implantation and other Applications of Ions and Electrons (ION2006), 26.-29.06.2006, Kazimierz Dolny, Poland

The mineralogy of Böttger stoneware

Kockelmann, W.; Kirfel, A.; Neelmeijer, C.; Walcha, H.-M.
In the early eighteenth century Johann Friedrich Böttger produced a remarkable type of red stoneware which is extraordinary hard and suitable for surface polishing. Although of considerable value for museums and collectors, surprisingly little is known of the elemental and mineral compositions of this type of stoneware. We have analysed Böttger objects and other red stoneware pieces from the Porcelain Collection of the State art Collections Dresden by non-destructive neutron-diffraction. The neutron analyses of about 20 intact jugs, vases and plates carried out at the spallation source ISIS provides a quantitative overview of the main mineral phase compositions. The data confirm the fine raw material selection by Böttger for the production of his stoneware. The mineral phase composition of Böttger objects, however, is not unique and similar to the also studied Yixing red stoneware.
Keywords:
Böttger stoneware, neutron diffraction, mineral phase analysis, material analysis

Advantages of the Superconducting 3½ Cell SRF Gun in Rossendorf

Staufenbiel, F.
This paper describes the features of the 3½ cell SRF gun from Rossendorf and the advantages and challenges of superconductivity. One advanced working regime of the SRF photo injectors is to produce short pulses with high bunch charges and low transverse emittance running in cw-mode. The quality of this electron beam is crucially for future FEL's with very short wave lengths. The main challenge is to compensate the growing transverse and longitudinal emittance with increasing bunch charges. Therefore, some procedures for emittance compensation for the 3½ cell SRF gun will be discussed.

BNL superconducting RF guns-technology challenges as ERL sources

Burrill, A.; Ben-Zvi, I.; Calaga, R.; Chang, X.; Hahn, H.; Kayran, D.; Kewisch, J.; Litvinenko, V.; Mcintyre, G.; Nicoletti, A.; Pate, D.; Rank, J.; Scaduto, J.; Rao, T.; Wu, K.; Zaltsman, A.; Zhao, Y.; Bluem, H.; Cole, M.; Falletta, M.; Holmes, D.; Peterson, E.; Rathke, J.; Schultheiss, T.; Todd, A.; Wong, R.; Lewellen, J.; Funk, W.; Kneisel, P.; Phillips, L.; Preble, J.; Janssen, D.; Nguyen-Tuong, V.
The design, fabrication and commissioning of a 703.75 MHz SRF photoinjector with a retractable multi-alkali photocathode designed to deliver 0.5A average current at 100% duty factor is the present undertaking of the electron cooling group in the Collider Accelerator Division of Brookhaven National Labs. This photoinjector represents the state of the art in photoinjector technology, orders of magnitude beyond the presently available technology, and should be commissioned by 2007. The R&D effort presently underway, and the focus of this paper, will address the numerous technological challenges that must be met for this project to succeed. These include the novel physics design of the cavity, the challenges of inserting and operating a multi-alkali photocathode in the photoinjector at these high average currents, and the design and installation of a laser system capable of delivering the required 10s of watts of laser power needed to make this photoinjector operational. (c) 2005 Elsevier B.V. All rights reserved.
Keywords:
energy recovery linac; high average current; superconducting RF; photoinjector design; ampere class; photocathode

Uranium as a stress factor in well aerated multispecies biofilms  A microsensor study of the O2 concentrations

Krawczyk-Bärsch, E.; Großmann, K.; Arnold, T.; Diessner, S.; Wobus, A.
Multispecies biofilms were cultured on glass slides in a standard culture medium (Sifin; TN 117) under air atmosphere in annular rotating reactors [1] for two months to obtain a thickness of approximately 800 µm. The slides with the grown biofilms were removed from one reactor for microsensor studies in a flow cell. Two other reactors were fed with UO2(ClO4)2 to adjust the total uranium concentration in the culture medium to 1x10-5 mol/l and 1x10-6 mol/l, respectively, i.e. the biofilms in these reactors were exposed to uranium for three weeks before they were removed for additional microsensor studies. Concentration profiles of oxygen versus biofilm depths were measured in each biofilm by electrochemical microsensors with a tip diameter of 10µm. A motor-driven micromanipulator was used for moving downwards through the biofilm in 20 or 50µm steps. The microsensor results clearly showed a significant dependence of the O2 concentration on the presence as well as on the concentration of uranium. In the absence of uranium the O2 concentration in the well aerated biofilm decreased slightly due to the aerophile microbes, dominating this biofilm. In contrast, O2 concentrations in the biofilms, which were exposed to different concentrations of uranium, decreased with increasing uranium concentration. Apparently, uranium acted as a stress factor for the microbes. Since metals have a strong effect on oxygen consumption, decreases in oxygen concentration could be due to changes in microbial activities [2] as well as on the activation of microbial communities induced by the addition of uranium [3]. 16S rDNA gene sequence retrieval and FISH are currently in progress to provide information on the changes occurring in the biofilm community and the resulting influence on the O2 concentration profiles.

Spectroscopic and microscopic characterization of uranium biomineralization in Myxococcus xanthus

Jroundi, F.; Merroun, M.; Arias, J. M.; Rossberg, A.; Selenska-Pobell, S.; González-Muñoz, M. T.
In this work, synchrotron-based X-ray absorption spectroscopy (XAS) and transmission electron microscopy (TEM) studies were carried out to elucidate at molecular scale the interaction mechanisms of Myxococcus xanthus with uranium at different pH values. Extended X-ray absorption fine structure (EXAFS) experiments show that there are significant differences in the structural parameters of the U complexes formed by this bacterium at pH 2 and 4.5. At very low acidic pH of 2, the cells accumulated U(VI) as organic phosphate-metal complexes. However, at pH 4.5, the cells of this bacterium precipitated U(VI) as meta-autunite-like phase. TEM indicated that at pH 2 the uranium accumulates are located mainly at the cell surface. Whereas, at pH 4.5 the uranium precipitation takes place on the cell wall and within the extracellular polysaccharides (EPS) characteristic of this bacterium. Dead/live staining studies showed that 30% and 50% of the uranium-cell treated cell populations are alive at pH 2 and 4.5, respectively. The precipitation of uranium as mineral phase is possibly due to the acid phosphatase activity which was detected at both pH values. Precipitation of U as mineral phase may lead to more stable U(VI) sequestration that may be suitable for remediation uses. These observations, combined with the very high uptake capacity of this bacterium, imply that bacterial cells may significantly influence the fate of uranium in soils where these bacterial groups are mainly found.

Anwand, W.; Skorupa, W.; Schumann, T.; Posselt, M.; Schmidt, B.; Grötzschel, R.; Brauer, G.
B+ and P+ ions were implanted into Ge wafers covered with an amorphous surface layer of 150 nm. After this, FLA in Ar atmosphere was used in order to realise three objectives:- recrystallisation of the amorphous region on top of the Ge wafer - electrical activation of the implanted ions- reduction of diffusion processes during the FLA. The heat treatment with Xenon flash lamps having a spectrum in the visible range of light and a pulse length of 3 or 20 ms allowed an ultra-short heating up of the near surface region. In this way, a modification of the structure of the amorphous layer containing the implanted range was possible. Depth profiles of defects, especially of the vacancy-type, were investigated by SPIS before and after FLA. It will be shown that the remaining vacancy-type defect structure depends on the parameters of the process of heat treatment, and that these defects could not be completely removed by FLA.These results will be compared with such from SRIM 2003 calculations (Stopping and Range of Ions in Matter) and Rutherford Backscattering Spectrometry.
Keywords:
Ge, ion implantation, flash lamp annealing, vacancy-type defects, slow positron implantation spectroscopy

Künstler, J.-U.; Veerendra, B.; Figueroa, S. D.; Sieckmann, G. L.; Rold, T. L.; Hoffman, T. J.; Smith, C. J.; Pietzsch, H.-J.
Bombesin (BBN) peptide exhibits high selectivity and affinity for the gastrin releasing peptide receptor (GRPr). The GRPr is over-expressed on many human cancer cell types, thus making BBN a potent delivery vehicle for radionuclide targeting. In this study, the biologically active minimal sequence BBN(7-14) was labeled using the novel Tc 4+1 mixed-ligand system, [Tc(NS3)(CN-R)], in which Tc(III) is co-ordinated by a monodentate isocyanide linker bearing the peptide and the tetradentate, tripodal chelator, 2,2,2-nitrilotriethanethiol (NS3). BBN(7-14) was N-terminally modified with Gly-Gly-Gly, ßAla and Ser-Ser-Ser spacer groups (X) and functionalized with 4-(isocyanomethyl)benzoic acid (L1) or 4-isocyanobutanoic acid (L2) resulting in a series of [M(NS3)(L-X-BBN(7-14))] conjugates (M = 99mTc, Re). The isocyanides ligand frameworks were introduced using novel bifunctional coupling agents. The spacer groups (X), the monodentate isocyanide units, and a tetradentate NS3 chelator bearing a pendant carboxylic acid (NS3COOH) were proposed as pharmacological modifiers. 99mTc-labeling was performed in a two-step procedure by first preparing 99mTc-EDTA/mannitol followed by reactions with the isocyanides and NS3 or NS3COOH ligand frameworks. The 99mTc-complexes were obtained with a radiochemical yield of 30 to 80% depending on the amount of the isocyanide (20 to 100 nmol) used. These new conjugates were purified by reversed-phased high performance liquid chromatography (RP-HPLC) to give a radiochemical purity of ≥ 95 %. The 99mTc-conjugates exhibited high in vitro stability (> 90 %, 24 h). Analogous nonradioactive Re-conjugates were synthesized and characterized by electrospray ionization mass spectrometry (ESI-MS). RP-HPLC analyses of the new Re-conjugates indicated that they exhibited identical retention times to the corresponding 99mTc-conjugates under identical HPLC conditions, demonstrating structural similarity between the two metallated species. The [Re(NS3)(L-X-BBN(7-14))] conjugates exhibited GRPr affinity in the nanomolar range as demonstrated by in vitro competitive binding assays using PC-3 human prostate cancer cells. In vitro internalization/externalization assays indicated that ~ 65% of [99mTc(NS3)(L2-βAla-BBN(7-14))] conjugate was either surface bound or internalized in PC-3 cells. Cell-associated activity for all other 99mTc-conjugates was below 20%. Biodistribution studies of [99mTc(NS3)(L-βAla-BBN(7-14))], L = L1, L2, in normal, CF-1 mice showed minimal accumulation in normal pancreas (a tissue expressing the GRPr in high density in rodent models) and rapid hepatobiliary elimination. Introduction of a carboxyl group onto the NS3 ligand framework had only minimal effects to increase renal excretion. Activity distribution and accumulation was highly dominated by the relatively lipophilic 4+1 complex unit.

Electromagnetic excitations in nuclei: from photon scattering to photodisintegration

Erhard, M.; Nair, C.; Beyer, R.; Grosse, E.; Junghans, A. R.; Klug, J.; Kosev, K.; Nankov, N.; Rusev, G.; Schilling, K. D.; Schwengner, R.; Wagner, A.
In explosive nucleosynthesis temperatures are high enough for photodisintegration reactions to occur, e.g. leading to the production of p-process nuclei. In order to understand the reaction rates of element production and element disruption we started an experimental program at the new bremsstrahlung facility of the superconducting electron accelerator ELBE of FZ Dresden-Rossendorf. The bremsstrahlung facility and the detector setup are designed such that the scattering of photons from nuclei and the photodisintegration of nuclei around the particle separation energies can be studied under optimized background conditions. In activation measurements with bremsstrahlung at end-point energy from 10.0 to 16.5 MeV (g ,p), (g ,n) and (g ,a) reactions of 92,100Mo have been studied. Our activation yields can be described within a factor 2-3 or better with calculations using the cross sections from recent Hauser-Feshbach models.

Status of the superconducting 3 1/2 cell SRF gun in Rossendorf

Simultaneous formation of two ripple modes on ion sputtered silicon

Keller, A.; Roßbach, S.; Facsko, S.; Möller, W.
The amorphized surface of Si(100) sputtered with low energy ions at moderate temperature was found to develop two perpendicular ripple patterns overlaying each other. The evolution of these patterns was studied over a wide range of fluence. Coarsening of both ripple modes was observed, showing a similar time dependence with a coarsening exponent of 1/z ~ 0.08. In the high fluence regime, the surface enters a steady state with both ripple modes still present.

Equilibrium concentration and diffusivity of vacancies and self-diffusion in Ge: An atomistic study

Geßner, H.; Posselt, M.
We developed an improved Stillinger-Weber-type potential for Ge by adjusting the three-body parameters in such a manner, that the potential yields the correct lattice constant and the correct cohesive energy, and the melting point and other properties are reproduced satisfactorily. Using this potential, the temperature dependence of equilibrium concentration and diffusivity of vacancies as well as the contribution of vacancies to self-diffusion are investigated by atomistic simulations and thermodynamic considerations. The enthalpies and entropies of formation and migration are calculated. Similar investigations are performed for self-interstitials in order to check whether their contribution to self-diffusion can be neglected, as shown experimentally. Finally, the self-diffusion coefficient and the equilibrium concentration of vacancies determined by the simulations are compared with experimental data from the literature.
Keywords:
Ge, vacancy, equilibrium concentration, diffusivity

Posselt, M.; Schmidt, B.; Anwand, W.; Grötzschel, R.; Skorupa, W.; Heera, V.; Gennaro, S.; Bersani, M.; Giubertoni, D.
P and As are considered the most suitable n-dopants in Ge. However, because of diffusion and deactivation effects it is difficult to achieve highly-n-doped Ge by ion implantation and subsequent annealing. We investigated high fluence P implantation into pre-amorphized Ge and subsequent annealing. The thickness of the amorphous layer was varied by implanting Ge at different energies. In all cases the main part of the as-implanted P profiles is located within this layer. Both RTA and flash-lamp annealing were employed. Considering samples with amorphous layers of different thickness enables detailed investigations of P diffusion in amorphous and crystalline Ge and solid-phase epitaxial regrowth during the post-implantation annealing. The thickness of the amorphous layers and the quality of the regrown crystalline Ge were monitored by RBS/C. The chemical depth profiles of P and the donor depth distributions were measured by SIMS and SRP, respectively. The results indicate that P diffuses much faster in amorphous Ge than in crystalline Ge. It is assumed that the P diffusivity in amorphous Ge shows a concentration dependence similar to that in crystalline Ge. The solid-phase epitaxial regrowth occurs already at the lowest thermal budget used in this work. It causes a considerable P redistribution and, presumably, the incorporation of P into crystalline Ge at concentrations above the equilibrium solubility.
Keywords:
Ge, n-doping, ion implantation, annealing

Damage accumulation in nitrogen implanted 6H SiC: Dependence on the direction of ion incidence and on the ion fluence

Zolnai, Z.; Ster, A.; Khanh, N. Q.; Battistig, G.; Lohner, T.; Gyulai, J.; Kotai, E.; Posselt, M.
The influence of crystallographic orientation and ion fluence on the shape of damage distributions induced by 500 keV N+ implantation at room temperature into 6H SiC is investigated. The irradiation was performed at different tilt angles between 0 and 4 with respect to the 0001 crystallographic axis in order to consider the whole range of beam alignment from channeling to random conditions. The applied implantation fluence range was 2.5 1014 3 1015 cm 2. A special analytical method, 3.55 MeV 4He+ ion backscattering analysis in combination with channeling technique (BS C), was employed to measure the disorder accumulation simultaneously in the Si and C sublattices of SiC with good depth resolution. For correct energy to depth conversion in the BS C spectra, the average electronic energy loss per analyzing He ion for the 0001 axial channeling direction was determined. It was found that the tilt angle of nitrogen implantation has strong influence on the shape of the induc! ed disorder profiles. Significantly lower disorder was found for channeling than for random irradiation. Computer simulation of the measured BS C spectra showed the presence of a simple defect structure in weakly damaged samples and suggested the formation of a complex disorder state for higher disorder levels. Full-cascade atomistic computer simulation of the ion implantation process was performed to explain the differences in disorder accumulation on the Si and C sublattices. The damage buildup mechanism was interpreted with the direct-impact, defect-stimulated amorphization model in order to understand damage formation and to describe the composition of structural disorder versus the ion fluence and the implantation tilt angle.
Keywords:
ion implantation, SiC, damage accumulation

Azaspirovesamicols-Regioselective Synthesis and Crystal Structure Analysis of a Novel Class of Vesamicol Analogues as Potential Ligands for the Vesicular Acetylcholine Transporter

Wenzel, B.; Bats, J. W.; Scheunemann, M.; Steinbach, J.
This report describes the high regioselectivity of nucleophilic epoxide ring-opening reactions which resulted in two of four possible regioisomers of N-benzoyl- (5a and 5b) and N-fluorobenzoylazaspirovesamicol derivatives (6a and 6b), respectively. Based on structural information obtained from X-ray crystal structure analyses of 5a and 5b the mode of epoxide ring-opening is discussed

Photocathode Laser for the Superconducting Photo Injector at the Forschungszentrum Rossendorf

Will, I.; Klemz, G.; Teichert, J.; Staufenbiel, F.
We report on the design of the photocathode laser for a superconducting RF gun, which is presently under development at the Forschungszentrum (FZ) Rossendorf. This laser is foreseen to drive the RF gun in CW mode with up to 1 nC bunch charge. It generates pulses of 12...14 ps duration with 500 kHz repetition rate and 0.8 μJ pulse energy at 263 nm wavelength. This should provide sufficient pulse energy for generation of bunches with 1 nC charge using caesium telluride photocathodes. Due to two active modelockers in the laser oscillator, the latter operates in tight synchronism to the RF master oscillator of the linac. The laser consists of a short-pulse oscillator, a pulse picking Pockels cell, a regenerative amplifier and a wavelength conversion unit. The latter converts the infrared laser radiation to the ultra-violet (UV). This unit turns out to be a particularly critical element of such a photocathode laser driving a RF gun in CW mode.

3-1/2 Cell Superconducting RF Gun Simulations

Beard, C. D.; Rogers, J. H. P.; Teichert, J.; Staufenbiel, F.
A 3-1/2 cell superconducting RF photocathode gun is being developed at Forschungszentrum Rossendorf to produce a high peak current, low emittance electron beam. This technology is essential to the realisation of many large scale facilities. The gun is designed for CW operation mode with 1 mA current and 9.5 MeV electron energy, and it will be installed at the ELBE superconducting electron linear accelerator. The gun will have a 3-1/2 cell niobium cavity operating at 1.3 GHz. The cavity consists of three cells with TESLA geometry and a specially designed half-cell in which the photocathode will be placed. Typical ERL-based projects require ~100 mA average current, and therefore suitable upgrade paths are required. Simulations have been carried out to evaluate the design and to determine suitable upgrades for higher current operation. Simulations of alternative cathode surface shapes are presented. Several couplers have been identified that can provide higher power to the cavity, whose integration and suitability has been verified. All the investigations that have identified possible solutions to higher current operation are discussed in this report.

The Radiation Source ELBE at Forschungszentrum Rossendorf

Michel, P.
The radiation source ELBE (Electron Linac of high Brilliance and low Emittance) at Forschungszentrum Rossendorf is based on a superconducting linac that produces a high power continuous wave (cw) electron beam up to 40 MeV and 1 mA. The linac is used to drive two free-electron lasers producing infrared radiation from 5 to 150 microns wavelength. Additionally, from several conversion targets MeV-bremsstrahlung (< 20 MeV) and X-rays (10-100 keV) from electron channelling are generated. In the future even neutron and positron beams will be available at ELBE. The used superconducting RF accelerator technology and details of the machine instrumentation, in particular the electron beam diagnosis will be described.

Nanoscaled semiconductor heterostructures for CMOS transistors formed by ion implantation and hydrogen transfer

Popov, V.; Tyschenko, I.; Cherkov, A.; Voelskow, M.
Abstract: Using bulk silicon can be ended for planar 22 nm technological node due to silicon mobility limitation. New type of substrates needs for further scaling in CMOS microelectronics. We speculate that these new type of materials will be semiconductor heterostructure on insulator (HOI) compatible with current silicon planar CMOS technology. In this work an effect of interface mediated endotaxial (IME) growth of thin semiconductor film at Si/SiO2 bonded interface was experimentally observed and investigated for the first time. Joint semiconductor material stack obtained by hydrogen transfer of one layer material (silicon) and second one (germanium or indium antimonide) placed on amorphous silicon dioxide film is presented. First of all thin film dual layer Si-Ge heterostructure properties were considered. Si-Ge HOI structures were obtained using Ge ion implantation in dioxide with followed Ge segregation to the interface between directly bonded silicon and silicon dioxide wafers. The method is also compatible with A3B5 thin film formation, as was shown for InSb film. Thermodynamic, kinetic and lattice mismatch parameter influences on IME process are considered.
Keywords:
hydrogen transfer; silicon films; implanted impurities; segregation; endotaxy

Ion beam synthesis of 4H-(Si1-xC1-y)Gex+y solid solutions

Pezoldt, J.; Kups, T.; Voelskow, M.; Skorupa, W.
4H-(Si1-xC1-y)Gex+y solid solutions with a Ge incorporation on lattice site from 0.7 to 2.5 percent were formed by ion beam synthesis. The concentration was varied from 1 to 20 % by implanting Ge at 600 C. The implanted samples were annealed at 1300 C in a rapid thermal processing equipment.
Keywords:
implantation Ge into SiC; RTA; RBS

Silicon-Germanium Heterostructure-on-Insulator formed by Ge+ Ion Implantation and Hydrogen Transfer

Popov, V. P.; Tyschenko, I.; Cherkov, A.; Voelskow, M.
Using bulk silicon can be ended for 32 nm technological nodes. New type of substrates needs for further scaling in CMOS microelectronics. We speculate that these new type of materials will be semiconductor heterostructure on insulator (SHI) compatible with current silicon planar CMOS technology. Joint semiconductor material stack placed on cheap amorphous dioxide is presented. First of all thin film SiGe heterostructure properties is considered. It was obtain using Ge ion implantation in dioxide with followed Ge segregation to the directly bonded interface between silicon and silicon dioxide wafers. The method is also compatible with A3B5 thin film formation.
Keywords:
Si-Ge heterostructures; ion implantation

Development of a Superconducting RF Photoinjector

Teichert, J.
A superconducting rf photo electron injector (SRF gun) is under development at the Forschungszentrum Rossendorf. The project aims at several issues: improvement of the beam quality for the ELBE superconducting electron linac, demonstration of feasibility of this gun type, investigation of critical components, and parameter studies for future application (BESSY-FEL, 4GLS). The design layout of the SRF photo-injector, the parameters of the superconducting cavity and the expected electron beam parameters are presented. The SRF gun has a 3+1/2-cell niobium cavity working at 1.3 MHz and will be operated at 2 K. The three full cells have TESLA-like shapes whereas the half-cell has an special form obtained from numerical optimization. In the half-cell a Cs2Te photocathode is situated which will be cooled by liquid nitrogen. In 2005, the main parts for He cryostat like vacuum vessel, cryogenic and magnetic shields were fabricated. Test benches for the cathode cooling system and the cavity tuner were assembled and the measurements performed. The photo cathode preparation lab has been arranged, and the diagnostic beam line has been designed. After delivery of the Nb cavity, its rf properties were measured. The cavity was tuned and its chemical treatment is started.

Rogozin, A.; Vinnichenko, M.; Shevchenko, N.; Vazquez, L.; Mücklich, A.; Kreissig, U.; Yankov, R. A.; Kolitsch, A.; Möller, W.
The paper correlates the growth and structure formation with the properties of indium-tin-oxide (ITO) films fabricated by pulsed reactive magnetron deposition onto amorphous substrates held at elevated temperatures ranging from RT to 510 °C. The evolution of the microstructure is consistent with the well-known structure zone model. The temperature dependence of the film texture is described with consideration of the interplay between the shadowing and surface diffusion processes. It is shown that deposition at elevated temperatures lowers the crystallization threshold and is more effective in reducing resistivity than the post-deposition vacuum annealing at comparable temperatures. The films grown at a substrate temperature of 400 and 510 °C have the lowest resistivity of 1.2*10^-4 Ohmcm, the highest free electron density of 1.2 - 1.0*10^21 cm^-3, and mobility of 35 - 42 cm^2V^-1s^-1 while showing the strongest (222) texture with the largest grain size.
Keywords:
indium-tin-oxide, reactive pulsed magnetron sputtering, electrical properties, texture

Fitting, H.-J.; Salh, R.; Schmidt, B.
Thermally oxidized SiO2 layers of 100 and 500 nm thickness have been implanted by oxygen and sulfur ions with a dose of 3x1016 and 5x1016 ions/cm2, respectively, leading to an atomic dopant fraction of about 4 at.% at the half depth of the SiO2 layers. The cathodoluminescence spectra of oxygen and sulfur implanted SiO2 layers show besides characteristic bands a sharp and intensive multimodal structure beginning in the green region at 500 nm over the yellow-red region extending to the near IR measured up to 820 nm. The energy step differences of the sublevels amount on average 120 meV and indicate vibration associated electronic states, probably of O2-interstitial molecules, as we could demonstrate by a respective configuration coordinate model.
Keywords:
ion implantation, SiO2, CL-luminesence

SiGe heterostructures-on-insulator produced by Ge+-ion implantation and subsequent hydrogen transfer

Tyschenko, I. E.; Cherkov, A. G.; Voelskow, M.; Popov, V. P.
Strong decrease in the carrier mobility of the nanometer-thick silicon films imposes a limitation on the application of silicon-on-insulator (SOI) structures in the current silicon planar CMOS technology. The formation of SiGe-heterostructures-on-insulator (HOI) is a way to increase the carrier mobility in the nanometer-scale layers. In this work, we present the results on the interface mediated endotaxial (IME) growth of thin Ge film from the Ge+-ion implanted SiO2 layer of the SOI structure.
Keywords:
SOI, implantation

Crystallization of InSb phase near the bonding interface of silicon-on-insulator structure

Tyschenko, I. E.; Cherkov, A. G.; Voelskow, M.; Popov, V. P.
Bonding interface of SOI structure may be an effective sink for impurity atoms because of higher concentration of vacancies and microvoids on the cleavage planes. The behaviour of ion-implanted Sb and In atoms near the bonding interface of SOI structures was investigated as a function of annealing temperature.
Keywords:
SOI, implantation, Sb, In

Process control and melt depth homogenization for SiC-on-Si structures during flash lamp annealing by carbon implantation

Smith, M. P.; Mcmahon, R. A.; Voelskow, M.; Skorupa, W.; Stoemenos, J.; Ferro, G.
Flash lamp annealing in the millisecond regime of heteroepitaxial silicon carbide on silicon structures involves melting the silicon below the SiC layer, but the deep faceted nature of the liquid-solid interface leads to unacceptable surface roughness. This paper describes a method of controlling melting by implanting a high dose of carbon at a controlled depth below the Si/SiC interface, which significantly alters the melting characteristics of the silicon. This technology has also been applied to SiC and Si multilayer heterostructures. Results confirm the effectiveness of this approach for increasing surface uniformity, making liquid phase processing compatible with standard device fabrication techniques. A thermal model has also been developed to describe this process and results indicate that the theoretical work is consistent with the experimental evidence. The model is a valuable tool for predicting the onset of melting, maximum temperatures, and process windows for controlled liquid phase epitaxy.
Keywords:
silicon carbide, ion implantation, flash lamp processing, liquid phase processing, modelling

Nazarov, A.; Osiyuk, I.; Tyagulskii, I.; Lysenko, V.; Prucnal, S.; Sun, J. M.; Skorupa, W.
This work is a comparative study of the processes of charge trapping in silicon dioxide layers doped with different rare-earth impurities (Gd, Tb, Er) as well as with Ge. Diode structures incorporating such oxide layers exhibit efficient electroluminescence (EL) in the spectral range from UV to IR. Ion implantation was performed over a wide dose range using doses chosen to provide impurity concentrations of 0.1 to 3 at. % with the implant profiles peaking in the middle of the oxide. Post-implantation anneals were carried out at different temperatures. An ITO layer was employed as the transparent gate electrode for the implanted SiO2/Si light emitting diodes (LEDs).Charge trapping was studied using an electron injection technique at constant current regime in the range of 1013 to 1021 e/cm2 with simultaneous measurements of the EL intensity. High-frequency C/V characteristics were used to control the net charge in the oxides. The I/V characteristics and the EL intensity vs. applied voltage were also measured.Analysis of the charge trapping and the variation of the EL intensity during electron injection shows that the current density range can be conveniently divided in three portions: (i) low injection level, where electron/hole capture at traps with a large capture cross-sections and low EL intensity occurs; (ii) medium injection level corresponding to the main operation mode of the LEDs (odd hole trapping depending on the injected current level is observed); and (iii) high injection level (electrical quenching of the EL, which correlates with electron capture at traps of extremely small capture cross-sections of about 10-21 cm2 takes place). The parameters of the hole and electron traps are determined. The nature of specific electron hole trapping at the medium injection level in RE doped MOSLEDs is discussed. Mechanisms of EL quenching at the high injection level are proposed.
Keywords:
chare trapping, electroluminescence, ion implantation, light emitting diodes, rare earths, germanium

Electrical activation of implantation-induced defects in ZnO by flash-annealing

Børseth, T. M.; Christensen, J. S.; Anwand, W.; Skorupa, W.; Svensson, B. G.; Kuznetsov, A. Y.
In this project we study diffusion and electrical activation in lithium and helium implanted ZnO single crystal wafers with high resistivity using secondary ion mass spectrometry (SIMS), scanning spreading resistance microscopy (SSRM) and scanning capacitance microscopy (SCM), respectively. Li+ ions were implanted with an energy of 837 keV at a dose of 2x1015 cm-2, and He+ were implanted with an energy of 683 keV at a dose of 6x1015 cm-2 to ensure similar implantation depths and damage productions. The samples were then annealed using short 20 ms light flashes corresponding to temperatures of 900°C, 1200°C and 1400°C. After each annealing step the samples were characterized with SSRM/SCM and SIMS. In as-implanted samples, no changes in the initially high resistivity are observed in neither the Li- nor the He-implanted samples but after the thermal treatments a substantial decrease is observed in both sets of samples. This resistivity drop is most likely related to electrical activation of shallow implantation-induced defects or deactivation of compensating defects/impurities, as He in principle should be electrically inactive in any solid state material. No significant redistribution of the implanted ions is observed.
Keywords:
zinc oxide. ion implantation, flash lamp annealing, electrical activation, SIMS, scanning spreading resistance microscopy, scanning capacitance microscopy

Formation of germanium shallow junction by Flash annealing

Satta, A.; DAmore, A.; Simoen, E.; Anwand, W.; Skorupa, W.; Clarysse, T.; van Daele, B.; Janssens, T.
We have investigated flash-lamp annealing (FLA) of germanium wafers doped with phosphorous and boron introduced in the crystal by ion implantation. Annealing was performed by using pre-heating at 400-450 oC in a conventional rapid thermal processing (RTP) unit and a fast (3-20 ms) FLA annealing at 800 oC or 900 oC. Diffusion of P is suppressed during the 800oC-20 ms FLA annealing, while concentration-enhanced diffusion occurs upon 900oC FLA anneals. At this higher temperature the FLA pulse time becomes a fundamental parameter, since the shortest FLA pulse (3 ms) causes less junction deepening and less P dose loss as compared to the longest (20 ms) pulse. Importantly, P activation seems to be enhanced by the FLA process. The FLA process applied to B-doped pre-amorphized Ge layers does not show advantages as compared to a RTP conventional annealing. B diffusion and activation behavior are indeed similar for the millisecond annealing approach and for a conventional RTP combined with a solid phase epitaxial regrowth of the doped Ge layer. In summary, the FLA technique holds a potential for the development of P shallow junctions in germanium wafers. However, junction stability following the FLA process is a concern and needs to be further investigated.
Keywords:
ion implantation, germanium, flash lamp annealing, diffusion, activation, RTP

Germanium shallow junction formation by flash annealing

Satta, A.; D'Amore, A.; Simoen, E.; Janssens, T.; Clarysse, T.; Anwand, W.; Skorupa, W.
We have investigated flash-lamp annealing (FLA) of germanium wafers doped with phosphorous and boron introduced in the Ge crystal by ion implantation. Annealing was performed by using pre-heating at 400-450 oC in a conventional rapid thermal processing (RTP) unit and a fast (3-20 ms) FLA annealing at 800 oC or 900 oC. Diffusion of P is suppressed during the 800oC-20 ms FLA annealing, while concentration-enhanced diffusion occurs upon 900oC FLA anneals. At this higher temperature the FLA pulse time becomes a fundamental parameter, since the shortest FLA pulse (3 ms) causes less junction deepening and less P dose loss as compared to the longest (20 ms) pulse. Importantly, P activation seems to be enhanced by the FLA process. The FLA process applied to B-doped pre-amorphized Ge layers does not show advantages as compared to a RTP conventional annealing. B diffusion and activation behavior are indeed similar for the millisecond annealing approach and for a conventional RTP combined with a solid phase epitaxial regrowth of the doped Ge layer. In summary, the FLA technique holds a potential for the development of P shallow junctions in germanium wafers. However, junction stability following the FLA process is a concern and needs to be further investigated.
Keywords:
germanium, ion implantation, flash lamp annealing, RTP, diffusion, electrical activation

Prucnal, S.; Sun, J. M.; Muecklich, A.; Skorupa, W.
The influence of different annealing processes (furnace annealing FA, rapid thermal annealing RTA and flash lamp annealing FLA) on the electroluminescence intensity, electric stability and point defect creation in SiO2 layers containing Gd atoms was investigated. The samples were annealed at different temperatures (from 800 to 10000C with the step 1000C for FA and from 10000C to 12000C with the step 500C for RTA and FLA). In the case of the peak at 316 nm which corresponds to Gd3+ the strongest EL intensity was observed from the sample annealed at 11000C after FLA. Increasing of the annealing temperature leads to a decreasing of the luminescence for each of annealing methods. The same effect was observed after increasing of the annealing time. In the case of defect formation under different annealing conditions an inverse situation was observed. Increasing of the annealing temperature and annealing time leads to an increase of the EL from oxygen deficiency centers (ODCs) An increase of the luminescence from defects at a simultaneous decrease of the luminescence from Gd at 316 nm can be explained by Gd-nanocluster creation in a-SiO2 during the annealing process.
Keywords:
flash lamp annealing, silicon-based light emission, electroluminescence, ion implantation

Prucnal, S.; Sun, J. M.; Reuther, H.; Skorupa, W.
The excitation mechanism of electroluminescence (EL) of cerium and erbium ions co-implanted with gadolinium into the SiO2 layer of MOSLEDs was investigated. Ce and Er ions were implanted into SiO2 with a concentration of 1% and 2%, respectively, subsequently implanted by gadolinium ions with concentrations of 0.5, 1.5 and 3%. Silicon dioxide containing cerium co-implanted with Gd exhibits two different excitation mechanisms: direct Ce3+ ion excitation by hot electrons and transfer of energy from 6PJ energy level of Gd to 5d energy state of Ce leading to an increase of the EL of Ce in the blue region. The EL observed from the sample containing 3% of Gd was 5 times higher in comparison with samples implanted only by Ce. The Er implanted SiO2 exhibits the typical peak at 1540 nm and weak luminescence in the green and blue region. Two green peaks correspond to the transitions from 2H11/2 and 4S3/2 to 4I15/2 and blue peaks to those from 2H9/2 and 4F5/2 to 4I15/2. The additional implantation of Gd leads to an increase of luminescence from Er3+ lines in the visible region caused by the energy relaxation from the Gd excited level 6PJ to the higher energy levels of erbium, whereas it has no influence on the infrared luminescence at 1.54 mm.
Keywords:
Gd sensitization, Cer, Erbium, energy transfer, silicon-based light emission, ion implantation, electroluminescence

Efficiency and Stability Issues of MOSLED´s made by RE Ion Implantation

Skorupa, W.; Prucnal, S.; Sun, J. M.; Helm, M.; Rebohle, L.; Gebel, T.; Nazarov, A.; Osiyuk, I.; Tjagulski, I.; Zuk, J.
Combining silicon-based electronic circuits with optoelectronic functionality is one of the key challenges for the future semiconductor technology. Such work must not only be devoted to the wavelength of 1.54 µm because there are more applications needing light sources from all the UV to IR wavelength range. In our work we employed ion beam processing to embed different rare earth (RE) luminescent centers (Gd3+, Ce3+, Tm3+, Tb3+, Eu3+, Er3+) into the silicon dioxide layer of a purpose-designed Metal-Oxide-Silicon-based Light Emitting Diodes (MOSLEDs) with advanced electrical performance. Efficient electroluminescence was obtained from UV to infrared with a transparent top electrode made of indium-tin oxide. The distinct differences in efficiency of the various rare earth atoms will be discussed as well as problems of electrical stability of such devices due to hot electron injection and charge trapping phenomena. Several developments for improving the device stability will be proposed related to charge compensation and elimination of the defects in SiO2.
Keywords:
Silicon-based light emitter, ion implantation, rare earths, electroluminescence, Metal-Oxide-Silicon-based Light Emitting Diodes (MOSLEDs), hot electron injection, charge trapping

Smith, M. P.; Seffen, K. A.; Mcmahon, R. A.; Anwand, W.; Skorupa, W.
A flash lamp has been proposed for annealing wafers with diameters approaching 100 mm.The equipment applies a pulse, with duration 0.5 ms to 20 ms, resulting in large transient thermalgradients in the wafer. In this paper, we present a model for the thermal reaction of this processand its effect upon the mechanical behaviour, in order to predict stresses, shape changes and tocapture practical phenomenon, such as bifurcation of deformation modes. We then use themodel to follow changes in the expected response consequent on altering process conditions, aswell as exploring important issues associated with scaling to large wafer sizes. The model isfurther used to predict material yielding leading to permanent deformations. This work presentsthe first description of the thermo-mechanical response of wafers to flash lamp annealing in themillisecond time regime and is therefore fundamental to the use of this technique in thefabrication of semiconductor devices.
Keywords:
Stress, Wafer, Flash lamp annealing

Process Control During Liquid Phase Rerowth of 3C-SiC on Si Substrates

Smith, M. P.; Voelskow, M.; Mcmahon, R. A.; Muecklich, A.; Anwand, W.; Skorupa, W.
Flash lamp annealing in the millisecond regime of heteroepitaxial silicon carbide on silicon structures involves melting the Si below the SiC layer, but the deep facetted nature of the solid-liquid interface leads to unacceptable surface roughness. This paper describes a method of controlling melting by implanting a high dose of carbon or germanium at a controlled depth below the Si/SiC interface, which significantly alters the melting characteristics of the silicon. Results confirm the effectiveness of these approaches for increasing surface uniformity, making liquid phase processing compatible with standard device fabrication techniques. A thermal model has also been developed to describe this process and results indicate that the theoretical work is consistent with the experimental evidence. The model is a valuable tool for predicting onset of melting, maximum temperatures and process windows for liquid phase epitaxy.
Keywords:
Silicon carbide, Silicon, Heteroepitaxy, Liquid phase epitaxy, Flash lamp annealing

Millisecond annealing with flash lamps: tool and process challenges

Gebel, T.; Rebohle, L.; Fendler, R.; Hentsch, W.; Skorupa, W.; Voelskow, M.; Anwand, W.; Yankov, R.
Sub-second annealing is one of the key issues to meet the requirements of the 45 nm technology node according to the ITRS roadmap. Therefore, over the past decade there has been great interest in techniques such as laser and flash lamp annealing (FLA). In addition, advanced ultra-fast annealing shows promise for technologies that are not directly related to Si device processing. The main reason for using FLA in alternative applications is the reduced thermal budget because of the short annealing time, which enables one to achieve high temperatures (> 500°C) in the near-surface region while keeping the substrate bulk relatively cold. This is of particularly high importance for the development of novel polymer-based electronics and flexible solar cell technologies, where the substrates cannot withstand temperatures in excess of 150°C. An overview of theoretical simulations and related results from FLA experiments for a variety of layered systems is given. The influence of the flash duration and intensity on the heat distribution and the resulting physical properties is considered. Design and performance issues of the FLA tools depending on the specific uses and technical requirements are addressed. Furthermore, topics covered include high-throughput applications e.g. for roll-to-roll production of polymer substrates. Results of a prototype tool for multi-flash processing up to a frequency of 1 Hz using a pulse duration of 1 ms are also discussed.
Keywords:
Flash lamp annealing, Silicon device processing, roll-to-roll production, polymer substrates, sub-second annealing

Advanced Thermal Processing of Semiconductor Materials in the msec-Range

Skorupa, W.
Sub-second annealing is one of the key issues to meet the requirements of the 45 nm technology node according to the ITRS roadmap. Therefore, over the past decade there has been great interest in techniques such as laser and flash lamp annealing (FLA). In addition, advanced ultra-fast annealing shows promise for technologies that are not directly related to Si device processing. The main reason for using FLA in alternative applications is the reduced thermal budget because of the short annealing time, which enables one to achieve high temperatures (> 500°C) in the near-surface region while keeping the substrate bulk relatively cold. This is of particularly high importance for the development of novel polymer-based electronics and flexible solar cell technologies, where the substrates cannot withstand temperatures in excess of 150°C. An overview of theoretical simulations and related results from FLA experiments for a variety of layered systems is given. The influence of the flash duration and intensity on the heat distribution and the resulting physical properties is considered. Design and performance issues of the FLA tools depending on the specific uses and technical requirements are addressed. Furthermore, topics covered include high-throughput applications e.g. for roll-to-roll production of polymer substrates. Results of a prototype tool for multi-flash processing up to a frequency of 1 Hz using a pulse duration of 1 ms are also discussed.
Keywords:
silicon, flash lamp annealing

Industrial Application of Gamma Ray CT

Hampel, U.; Bieberle, A.; Schleicher, E.; Hoppe, D.; Zippe, C.
Gamma ray CT is a powerful tool for the measurement of phase fraction distributions in thermal hydraulic systems and process diagnostics applications. Challenging process and plant conditions, such as high pressures and temperatures, opaque metallic vessels or machine parts as well as thermally unsteady and electromagnetically noisy environments limit the range of applicable measurement techniques in real processes. Gamma ray CT is a non-invasive technique and can be applied without major modification of the process facility. The tomography equipment is still not too bulky and complex to enable industrial measurements outside the laboratory. Recently our group has developed a high resolution gamma ray CT system that comprises a Cs-137 isotopic source (165 GBq activity, 622 keV photon energy) and a 320 channel scintillation detector that employs highly compact and robust avalanche photo detector technology in combination with fast LYSO scintillation crystals. The detector is operated in gamma photon counting mode. The spatial resolution of the detector is 2 mm. For measurements at industrial facilities we further devised a tomograph gantry that consists of a vertical translational and a rotational motor driven unit for tomographic scans at different axial planes of an object. The vertical operating range is approximately 1800 mm and objects of up to 900 mm diameter can be scanned.
Keywords:
gamma ray CT, computed tomography

Grynszpan, R. I.; Baclet, N.; Darque, A.; Flament, J. L.; Zielinski, F.; Anwand, W.; Brauer, G.
In spite of previous extensive studies, the helium behavior in metals still remains an issue in microelectronics as well as in nuclear technology. A goldsilver solid solution (Au60Ag40: synthetic gold-rich electrum) was chosen as a relevant model to study helium irradiation of heavy metals. After helium-3 ion implantation at an energy ranging from 4.2 to 5.6 MeV, nuclear reaction analysis (NRA) based on the 3He(d,p)4He reaction, was performed in order to study the thermal diffusion of helium atoms. At room temperature, NRA data reveal that a single Gaussian can fit the He-distribution, which remains unchanged after annealing at temperatures below 0.45 of the melting point. Slow positron implantation spectroscopy, used to monitor the fluence dependence of induced defects unveils a positron saturation trapping, which occurs for He contents of the order of 50100 appm, whereas concentrations larger than 500 appm seem to favor an increase in the S-parameter of Doppler broadening. Moreover, at high temperature, NRA results clearly show that helium long range diffusion occurs, though, without following a simple Fick law.

Heller, R.; Facsko, S.; Kost, D.; Zschornack, G.
Due to their high amount of potential energy highly charged ions induce various changes in morphology and electronic structure of solid surfaces [1,2]. The potential energy which is the sum of the ionization energies of all removed electrons, is released on a very small localized area of a few nm2 and in very short times of tens of fs. Hence the power density deposited into the surface can reach values of up to 1014 Wcm−2 depending on the ions incident charge state. The changes in surface topology depend strongly on the electronic excitation in the surface and its lateral and longitudinal confinement. Focus of our investigations is the interaction of slow HCIs with surfaces that have a high confinement of excitation. Such surfaces are mainly all kind of insulators, but also samples with an additional confinement due to a layered structure. In this case the electron transfer between different layers is suppressed and the interacting system becomes quasi two dimensional. Investigations were performed at the Rossendorf Two Source Facility, an ion beam facility consisting of two sources: a 14.5 GHz ECR ion source and an Electron Beam Ion Source, the Dresden EBIT [3]. Ions of both sources are decelerated by a common deceleration unit to suppress kinetic effects during ion surface interaction. The combination of these both sources offers ions of various charge states (up to q = 44 for Xe), species (He, Ne, Ar, Xe, C, N, O) and kinetic energies (<q · 100 eV to q · 25 keV). We present scanning probe microscopy studies of surface modifications induced by single ion impacts. HOPG, MICA and ultra thin SiO2 layers were irradiated with ions of argon (charge states q = 1...16) and xenon (charge states q = 1...40). The diameter and the height of created nano structures wer e investigated in dependence on the ion charge state for both ion species. Additional to SPM investigations Raman spectroscopy of HOPG before and after irradiation was performed to get information about structural changes induced by the HCI impact.
Keywords:
Highly Charged Ions, Surface Interaction, HOPG, Excitation, STM

The Rossendorf Two Source Facility – A Device for the Observation of the Interaction of Slow Highly Charged Ions with Surfaces

Heller, R.; Facsko, S.; Kost, D.; Zschornack, G.
The interaction of slow highly charged ions with solid surfaces is mainly characterized by the high amount of potential energy stored in the ions and discharged on the surface. Thereby the potential energy is the sum of the ionization energies of all removed electrons. While the kinetic energy of an ion scales linearly with the charge state, its potential energy grows rapidly with each removed electron. Figure 1 shows the ionization energy and the resulting potential energy of iron ions of different charge states. The ion bombardment of solid surfaces with HCIs can lead to various changes in surface morphology [1-4]. The Rossendorf Two Source Facility presents a world wide unique ion beam facility consisting of two ion sources and providing ions of adjustable charge state and kinetic energy. These two sources are: a 14.5 GHz-Electron-Cyclotron-Resonance (ECR) ion source (Super Nanogan / Pantechnik) and an Electron Beam Ion Trap (Dresden EBIT / Leybold Vacuum Dresden GmbH) operating at room temperature [5,6,7].
Keywords:
highly charged ions, surface interaction, nano dots, STM, HOPG

Extraktion hochgeladener Ionen aus der Dresden EBIT im Überlaufregime

Heller, R.; Zschornack, G.
For the first time the production and the extraction of highly charged ions from the Dresden EBIT using the so-called leaky mode, an operating mode with a continuous ion extraction (DC) at fixed axial trap potantial was investigated. Measurements of the ion output current at a Faraday cup directly behind the source were done with integral ion currents of up to 1.5nA depending on the source parameters. Also the charge state distribution of the extracted ions at leaky mode was investigated. It was shown, that ions of argon gas can be extracted up to a charge state of q=17 with an ion current of 1pA (DC) and xenon ions up to a charge state of q=21 with currents of about 0.5pA (DC).
Keywords:
highly charged ions, leaky mode, EBIT